reliability and validity in diagnosis and classification of sz

Question 1

define reliability in diagnosis of SZ

Answer 1

the extent to which psychiatrists give the same diagnosis when assessing patients

Question 2

what 2 ways can the reliability of diagnosis be assessed in SZ?

Answer 2

through the 2 diagnostic manuals
- DSM-5
- ICD-10

Question 3

how do the diagnostic manuals ensure reliability?

Answer 3

they are diagnosing patients based on the same principles

Question 4

who researched into inter-rater reliability of SZ diagnosis

Answer 4

Cheniaux

Question 5

outline Cheniaux’s research into inter-rater reliability of SZ diagnosis

Answer 5

• 2 psychiatrists independently diagnosed 100 patients, using the DSM and ICD criteria for SZ
• psychiatrist 1:
  26 DSM
  44 ICD
• psychiatrist 2:
  13 DSM
  24 ICD

Question 5

what does Cheniaux’s research show about the reliability of SZ diagnosis?

Answer 5

it suggests both low inter-observer reliability and low reliability between the 2 classification systems
-subjective

Question 6

define validity in diagnosis of SZ

Answer 6

refers to how accurately SZ is diagnosed, this is tested through criterion validity

Question 7

outline soderberg’s research into validity of SZ diagnosis

Answer 7

reported a concordance rate of 81% using the DSM, suggesting it’s more reliable than the ICD as symptom criteria is more specific

Question 8

outline nilsson’s research into validity of SZ diagnosis

Answer 8

found only a 60% concordance rate between practitioners using the ICD, implying the DSM is more reliable

Question 9

what are the wider implications of SZ diagnosis?

Answer 9

• patients who are in need of help may not be receiving it, putting themselves at harm
• there are harmful side effects when wrongly taking anti-psychotics
• it is just as unethical to not diagnose patients
• social skills are an important part of treatment, by not working etc, patients are missing out on this

Question 10

what is symptom overlap in SZ

Answer 10

SZ shares symptoms with other psychological disorders, such as depression and bipolar disorder

Question 11

what is gender bias in SZ

Answer 11

gender bias occurs when the accuracy of diagnosis is dependent on the gender of the individual
- this may be due to gender-biased diagnostic criteria or clinicians basing their judgements on stereotypical beliefs

Question 12

what is culture bias in SZ

Answer 12

research suggests that there is a significant variation between cultures when it comes to diagnosing SZ.
- for example, African-Americans and Afro-Carribean’s are several times more likely to be diagnosed with SZ

Question 13

evaluation: reliability

Answer 13

ID: there is poor reliability in diagnosis
Q: important that 2 mental health professionals agree on diagnosis
EV: Cheniaux et al, 2 independent psychiatrists did diagnosis using DSM and ICD
1 - 26 sz with DSM, 44 ICD
2 - 13 sz with DSM, 24 ICD
AN: low inter-rater reliability as cannot agree, all subjective

Question 14

evaluation: symptom overlap

Answer 14

ID: symptoms overlap for different illnesses
Q: schizo and bipolar involve positive symptoms and negative symptoms
EV: ICD could be diagnosed schizo, but be bipolar under DSM
AN: questions the practical application of diagnosing through symptoms

Question 15

evaluation: comorbity

Answer 15

ID: there is a significant co-morbidity (high frequency of diagnosis of two disorders together) between
schizophrenia and other mental health disorders
Q: such as OCD and post-traumatic stress disorder
EV: Buckley et al (2009). The researchers found that 29% of their SZ patients suffered from post-traumatic stress disorder, whilst 50% suffered depression. This suggests that if schizophrenia is so frequently diagnosed with other psychiatric
disorders, then these two disorders may actually be the same, and so a more accurate and valid
method of diagnosis would be to combine these two.
AN: therefore, there are issues of validity in the diagnosis of SZ and attempting to differentiate its symptoms from that of other disorders.

Question 16

evaluation: culture bias

Answer 16

ID: another type of bias which may reduce the validity of the diagnosis of SZ is the problem of culture bias
Q: as suggested by research from Escobar et al
EV: for example, African Americans are far more likely to be diagnosed with SZ compared to patients belonging to Western cultures. for example, the phenomenon of hearing voices may be considered a desirable sign of increased spirituality and connectedness with ancestors, and so may even be encouraged. however, both classification systems would view this as a characteristic of SZ
AN: could increase the likelihood
of false diagnoses.